Method of operating compound compressed-air engines.



C. B. HODGES.

METHOD OF OPERATING COMPOUND COMPRESSED AIR ENGINES.

APPLICATION FILED JUNE 11, 1909. 953,335. Patented Mar. 29, 191.0.

2 SHEETS-*SHEET 1.

mvm'ma. 65% W h WI TN ES-SES.,

Walt

G. B. HODGES. METHOD OF OPERATING COMPOUND COMPRESSED AIR ENGINES.

APPLICATION FILED JUNE 11, 1909. 7 953,335., Patented Mar. 29, 1910.

2 SHEETS-SHEET 2.

1% N ESS m; 2m;-

III

STATES ATN FFIQE.

CHARLES B. HODGES, OF PITTSBURG, PENNSYLVANIA, ASSIGNOR TO H. K. PORTERCOMPANY, OF PITTSBURG, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA.

METHOD OF OPERATING COMPOUND COMPRESSED-AIR ENGINES.

To all whom it may concern:

Be it known that I, CHARLES B. Honors, a resident of Pittsburg, in thecounty of Allegheny and State of Pennsylvania, have invented a new anduseful Improvement in Methods of Operating Compound Compressed-AirEngines; and I do hereby declare the following to be a full, clear, andexact description thereof.

My invention relates to a method of operating compound compressed airengines, its object being to so operate the same as to insure themaintenance of the surface of the air inter-heater in proper conditionfor the proper reheating of the air expanded within the high pressurecylinder and insure the proper operation of the engine.

It consists, generally stated, in carrying the compressed air at highpressure through and expanding it within the high pressure cylinder andthereby reducing it below atmospheric temperature, confining suchexhaust air within a receptacle having extended exposed surfaces andreheating the same by inducing over such exposed surfaces a violentcurrent of air at atmospheric temperature suflicient to scour from orprevent the formation of frost on such surfaces, thereby reheating andincreasing the volume of such exhaust air and carrying the reheated airthrough the low pressure cylinder.

It also consists of certain other improvements as hereinafter set forthand claimed.

In the accompanying drawing Figure 1 is a side View of a locomotiveengine adapted for the use of the invention; Fig. 2 is a side viewpartly broken away on the opposite side thereof; Fig. 3 is a crosssection on the line 3-43 Fig. 2; Fig. 4 is an en larged longitudinalsection of the interheater and Fig. 5 is a cross section thereof; Fig. 6is a detail View of one end of the inter-heater showing other means ofinducing the violent current through the same.

In the original development of the compound compressed air engine suchas illustrated in Letters Patent No. 868,560 granted to me October 15th,1907, difliculty was encountered in the gathering of frost upon theexposed surfaces of the inter-heater, and as such frost acted as anon-conductor it prevented the rapid reheating of the compressed airafter it was expanded in the high Specification of Letters Patent.

Application filed June 11, 1909.

Patented Mar. 29, 1910.

Serial No. 501,642.

clog and close the tubes of the inter-heater and so reduce the amount ofair carried through the tubes and diminish the reheating action of theatmospheric air and as the compressed air within the inter-heater was ata very low temperature, ordinarily entering the same 100 or more degreesF. below atmospheric temperature, the frost covering the tubes of theinter-heater would gradually increase in thickness so as to almost closethe same. By the present invention I am enabled to overcome thisdifficulty and provide for the successful operation of the engine evenwhere the surrounding atmosphere is of very low temperature, in factbelow Zero F. The apparatus best adapted for the practice of theinvention is illustrated in the accompanying drawings as applied to alocomotive, having the main air reservoir 1 supported on suitablelocomotive truck or under-frame 2 mounted on the driving wheels 3 and 4on two sides of the locomotive.

On the high pressure side as shown in Fig. l the high pressure engine isshown at 5 connected up to the wheels 3, while on the other side the lowpressure engine is shown at 6 connected up to the wheels 4, said wheelsbeing secured to the axles 7. The auxiliary reservoir 8 is supported onthe main reservoir 1 and air is fed thereto from the main reservoirthrough a suitable reducing valve 9 bringing the air to proper pressurefor entrance to the valve chest 10 of the high pressure cylinder 11. Thepipe 12 leads to the high pressure cylinder and located therein is theoperating or throttle valve 13 which is connected by the rod 14 to thethrottle lever 15. The pipe 16 leads from the exhaust of the highpressure cylinder 11 to the inter-heater l7 and the pipe 18 leads fromthe interheater to the valve chest 19 of the low pressure cylinder 20from which cylinder the air exhausts. In the preferred construction Ilocate in the pipe 18 a stop valve 21 to hold the air within theinter-heater upon the closing of the throttle valve, said stop valvebeing actuated by the fluctuations of pressure in pipe 12 transmittedthrough ipe 22, as described in application for patent filed by meOctober 26, 1908, Serial No. 459,642. The preferred form of interheateris illustrated in Figs. 2, 4 and 5, being supported in horizontalposition on the pressure cylinder. This frost also tended to side of themain reservoir and extending for practically the full length thereof andbeing of small diameter and relatively great length, and is filled witha large number of small tubes to provide for a relatively strong orviolent draft of air through the tubes thereof for reheating thecompressed air. For example, in practical use I have found that with thecylinders 5 and 10 inches in diameter by 10 inches stroke, the best formof inter-heater is made of a casing 23 about 7 feet long and about 8inches inside diameter, this inter-heater being filled with a largenumber of tubes 24L extending for the full length of the inter-heaterseated in the end walls 25, 26 thereof, the tubes being of smalldiameter, for example, about 30 tubes 1-inch diameter being employed. Ialso prefer to employ within the inter-heater a suitable series ofbattles 27 between the tubes 24c so as to cause the compressed air to bereheated to travel in circuitous course around said reheating tubes. Toinduce the draft or current of atmospheric air through the inter-heatertubes I may employ different means, for example, in Fig. 2 I have illustrated the apparatus where air under pressure is utilized to induce thedraft through the inter-heater. In such case I form at the exhaust endof the inter-heater the nozzle 28, and entering the same is the air jet29, this jet being connected up to any part of the apparatus from whichair under pressure can be drawn.

I prefer to draw the air for inducing the draft from the pipe 18 betweenthe stop valve 21 and the valve chest 19 of the low pressure cylinder,as in this way said stop valve in preventing the escape of compressedair from the inter-heater upon the closing of the main throttle valvealso cuts off the air from the air et 29, there being no escape of airtherefrom except when the engine is in operation. To this end I employthe pipe 30 leading from the pipe 18 and having located therein thevalve 21 controlling the amount of air escaping from the air et pipe,and to obtain a stronger inducing current the air jet is of annular formas shown at 32, for example being formed of a ring pipe with a series ofjet orifices. To induce the draft through the interheater I may alsoutilize the exhaust from the low pressure cylinder as illustrated inFig. 2, employing the same either alone or in addition to the air underpressure entering through the pipe 30. In such case the exhaust pipe 33leads from the low pressure cylinder 20 and discharges into the nozzle28 of the inter-heater and may communicate with the pipe 30 supplyingair under pressure. This provides for the use both of the exhaust airfrom the low pressure cylinder and of air under pressure, so insuringthe formation of a suf ficiently violent draft for the securing of thetubes of the inter-heater as hereafter described. For the same purpose Imay also employ an independent fan for inducing the draft through theinter-heater as illustrated in Fig. 6. In this case the fan 35 islocated within the tubular extension of the inter-heater 37 at thedischarge end thereof and the fan is illustrated as driven by a,suitable air motor or turbine 38 operated by air under pressure drawnfrom any suitable part of the apparatus, such for example, as from thepipe 18 between the inter-heater and the low pressure engine.

In the practice of the invention with the apparatus above described, thecompressed air is stored at relatively high pressure, usually about 800pounds, within the main reservoir 1, and it is maintained within theauxiliary reservoir 8 at the desired pressure for the operation of theengine, say, at about 250 pounds. Upon the operation of the throttlevalve 13 the air passes to the cylinder 11 of the high pressure engineand generates power therein, escaping therefrom at a relatively lowpressure, for example, in the best practice at a pressure of aboutpounds.

The sudden and rapid expansion of the air within the high pressurecylinder causes a violent drop in the temperature of the air, this inturn contracting the same and reducing its volume. For example the airenters the high pressure cylinder at F., and it passes therefrom at atemperature far below atmospheric temperature, the reduction intemperature being usually about 140 F. so that it is brought to atemperature of about 80 below zero. If the air were allowed to enter thelow pressure cylinder at this temperature such cylinder would have to besmaller or the pressure less, and in either case the amount of work donein the low pressure cylinder would be much reduced, the size of thecylinder or the pressure of the air being reduced approximately onethird. By the passage of the air through the interheater as abovedescribed the temperature is restored as such pressure is increased involume so that I am enabled to obtain the same power in the low pressurecylinder which would have been obtained had no drop in temperatureoccurred. The difference between the temperature of the exhaust air whenit leaves the high pressure engine and atmospheric temperature is sogreat that it quickly causes condensation of moisture carried in theatmosphere which forms as a coating of frost over the exposed surfacesof the inter-heater, such as within the tubes 24: thereof, and as abovestated this frost coating serves as a non-conductor and prevents thefull reheating action of the atmospheric air passing through theinter-heater, and gradually gathers so that unless removed it will clogand partially close the tubes thereof so reducing the current of aircarried therethrough. To keep the tubes of the inter-heater clear fromfrost and maintain the full action of the atmospheric reheating I inducea very violent draft through the tubes of the inter-heater by thesuction or forcing action obtained in any suitable way, such as by airunder pressure as shown in Fig. 2, or by the exhaust air from the lowpressure cylinder as shown in said figure, or both, or by means of thefan as shown in Fig. 6. Such violent draft of atmospheric air throughthe tubes of the inter-heater acts to scour over the surfaces thereof onaccount of the large amount of atmospheric air carried through the smalltubes gives a sufficient reheating of the compressed air within theinterheater to prevent the formation of frost on the exposed surfaces ofsuch tubes and to scour off any such frost in case it is formed therein,so keeping the tubes of the interheater clear from frost and enablingthe air carried therethrough to impart its full reheating action to thecompressed air confined within the inter-heater. I have found that byproviding such violent scouring draft through the tubes of theinter-heater I am enabled to keep such tubes clear from frost even whenoperating the engine at atmospheric temperatures considerably below zeroF., and thus obtain the eflicient operation of the engine under suchextreme conditions. Where the exhaust from the low pressure engine isinsuflicient for this purpose it may be supplemented as above described,by the use of compressed air, and the amount of air under pressure usedcontrolled by the valve 81 within the air jetpipe 30 leading from thepipe 16 between the inter-heater and the low pressure cylinder. Asthrough the stop valve 21 in said pipe the escape of air from theinterheater is prevented upon the closing of the main throttle valve noair under pressure is wasted for the operation of the inter-heater whenthe engine is not in operation but it is automatically fed to the airjet as soon as the throttle valve is open and the stop valve is openedto admit air from the inter-heater to the low pressure engine.

The general method of operating com pressed air engines in which the airat high pressure is carried through one cylinder and thereby reducedbelow highest atmospheric temperature and the exhaust air therefrom isreheated when confined by extended exposure to air at atmospherictemperature and is then carried through a low pressure cylinder, and thespecific methods in which exhaust air from the low pressure cylinderwhile still under pressure is discharged to induce a draft over theexposed surface of the interheating receptacle, form the subject matterof application filed by me of even date herewith Serial No. 501,641. Theapparatus for producing a draft over the exposed surface of theinterheater by means of a fan, as illustrated in this application, formsthe subject matter of an application filed by me of even date herewithSerial No. 501,640. The construction of the interheater and theconnections taken from the pipe leading to the low pressure cylinder forproviding air for inducing a draft over the exposed surface of theinterheater, form the subject matter of an application filed by me ofeven date herewith Serial No. 501,648.

What I claim is:

1. The method of operating compound compressed air engines, consistingin carrying the compressed air at high pressure and expanding it withinone cylinder and thereby reducing it below atmospheric temperature,confining such exhaust air from said cylinder within a receptacle andinducing over the exposed surfaces of said receptacle a violent currentof air at atmospheric temperature sufficient to scour from or preventthe formation of frost on the exposed surfaces of said receptacle andthereby reheating and increasing the volume of such exhaust air and itscapacity to generate power, and carrying the reheated air through a lowpressure cylinder.

2. The method of operating compound compressed air engines, consistingof carryingthe compressed air through and expanding it within onecylinder and thereby reducing it below atmospheric temperature,confining such air within a receptacle having a series of tubes passingthrough the same and inducing a violent current of air at atmospherictemperature through the tubes of such receptacle sufficient to scourfrom or prevent the formation of frost therein, thereby reheating andincreasing the volume of such exhaust air and carrying the reheated airthrough a low pressure cylinder.

3. The method of operating compressed air engines, consisting incarrying the air at high pressure through one cylinder, confining theexhaust air therefrom within a receptacle having extended exposedsurfaces and then through a low pressure cylinder, and inducing acurrent of air at atmospheric temperature over the surfaces of theconfining receptacle by a jet of air at as high pressure as thatentering the low pressure cylinder.

In testimony whereof, I the said CHARLES B. Honcns have hereunto set myhand.

CHARLES B. HODGES.

Witnesses ROBERT C. ToT'rEN, J. F. WILL.

